Referring to FIG. 1, U.S. Pat. No. 5,293,747 discloses a conventional pneumatic tool 1 that includes a tool body 11, a pneumatic motor 12, a switching valve 13 and an operating bar 14. The tool body 11 is formed with an air inlet 111 and an air outlet 112. The pneumatic motor 12 is disposed in the tool body 11, and includes a cylinder 123 that defines an air chamber 120 and spaced-apart first and second flow channels 121, 122 communicating fluidly with the air chamber 120, and a rotor 124 that is disposed rotatably in the air chamber 120. The switching valve 13 is formed with a passage 131 and a notch 132, and is switchable between a first state where the passage 131 communicates fluidly the air inlet 111 and the first flow channel 121 and the notch 132 communicates fluidly the second flow channel 122 and the air outlet 112, and a second state where the passage 131 communicates fluidly the air inlet 111 and the second flow channel 122 and the notch 132 communicates fluidly the first flow channel 121 and the air outlet 112. The operating bar 14 is connected to the switching valve 13, extends outwardly from the tool body 11, and is operable to switch the switching valve between the first and second states such that the rotor 124 is rotatable in two opposite rotational directions.
During operation of the conventional pneumatic tool 1, the switching valve 13 needs to contact air-tightly the cylinder 123 by high air pressure of compressed air entering the tool body 11 via the air inlet 111 to ensure the work efficiency of the compressed air. However, since the switching valve 13 is directly connected to the operating bar 14, the switching valve 13 may not be in air-tight contact with the cylinder 123 due to structural interference among the tool body 11, the operating bar 14 and the switching valve 13. Moreover, the switching valve 13 may be moved to generate a gap between the switching valve 13 and the cylinder 123 due to unintended operation or touch of the operating bar 14.